Teen girl shot in back

A 13-year-old girl has been shot in the back in what police say is a targeted attack at a home in Sydney's west.

Three men, one armed with a shotgun, arrived at a home on Sunnyholt Road at Blacktown about 11pm (AEDT) on Monday and had a brief argument at the front door before the man inside closed the door on them.

As the three men left the property, several shots were fired into the home, one of which hit a 13-year-old girl in the back, police say.

She was taken to Westmead Hospital, where she is in a stable condition.

A woman and her two sons who were also home at the time were not injured.

Meanwhile, police say shots were fired at a three-storey townhouse in Blaxell Street in Granville on Sunday night, but the incident was not discovered by police until Monday afternoon, when they went to the house for an unrelated matter.

A crime scene was established and a number of items were seized for forensic examination.

Police have conducted a canvass of the neighbourhood and are now appealing for information.

The shootings are the latest in a spate of gun attacks during the last two weeks.